Drive unit

Abstract

To provide a drive device for a vehicle.SOLUTION: A drive device for a vehicle includes: a motor; a gear unit mechanically connected to the motor; a power conversion unit electrically connected to the motor; a casing; and a cooling system that circulates a heat medium in at least one of a first chamber and a second chamber. The casing has the first chamber and the second chamber separated from each other by a partition wall. The casing houses at least one of the motor and the gear unit in the first chamber and houses the power conversion unit in the second chamber. The cooling system includes a partition-wall cooling path for supplying the heat medium to the partition wall. The cooling system supplies the heat medium to the partition-wall cooling path more when a vehicle speed of the vehicle is low and output torque of the motor is high than that when the vehicle speed is high and the output torque is low.SELECTED DRAWING: Figure 1

Description

Technical Field

[0005]

[0001] The technology disclosed in this specification relates to a drive device for vehicles.

Background Art

[0002] The drive device for vehicles disclosed in Patent Document 1 has a configuration in which a case housing a power conversion unit and a case housing a motor are integrally connected. In this drive device, fins for air cooling are provided on a partition wall separating the power conversion unit and the motor.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the drive device of Patent Document 1, optimization of cooling has not been considered. Then, during low - speed operation when the running wind cannot be expected and cooling becomes difficult, or during high - torque operation when the heat generation amount of the motor increases, the amount of heat transfer from the motor to the power conversion unit may become large. As a result, due to an increase in the heat load, the lifespan of various electronic components of the power conversion unit may decrease.

Means for Solving the Problems

[0005] The vehicle drive system disclosed herein comprises a motor, a gear unit mechanically connected to the motor, a power conversion unit electrically connected to the motor, a casing, and a cooling system for circulating a heat transfer medium to at least one of a first chamber and a second chamber. The casing has a first chamber and a second chamber separated from each other by a partition wall. The casing houses at least one of the motor and the gear unit in the first chamber and the power conversion unit in the second chamber. The cooling system includes a partition wall cooling path that supplies a heat transfer medium to the partition wall. The cooling system includes a partition wall cooling path that supplies a heat transfer medium to the partition wall, and the amount of heat transfer medium supplied to the partition wall cooling path is greater when the vehicle speed is low and the output torque of the motor is high than when the vehicle speed is high and the output torque of the motor is low.

[0006] The heat transfer medium can take various forms. For example, the heat transfer medium may be oil, water, air, etc. With the above configuration, the amount of heat transfer medium supplied to the bulkhead cooling path can be appropriately adjusted according to the vehicle speed and output torque. The bulkhead can be cooled even under conditions where cooling the bulkhead is difficult (e.g., low vehicle speed conditions, high torque conditions). Since the amount of heat transferred from the motor to the power conversion unit can be suppressed, it is possible to suppress the increase in the heat load of the power conversion unit. [Brief explanation of the drawing]

[0007] [Figure 1] This diagram shows the schematic configuration of the drive unit 1. [Figure 2] This is an example of the torque curve TC of motor 40. [Figure 3] This is a table showing the allocation of oil supply. [Figure 4] This diagram shows the schematic configuration of the drive unit 101. [Figure 5] This figure shows the schematic configuration of the drive unit 201. [Figure 6] This figure shows the schematic configuration of the drive unit 301. [Figure 7] This figure shows the schematic configuration of the drive unit 401. [Modes for carrying out the invention]

[0008] The cooling system may gradually or continuously increase the amount of heat transfer medium supplied to the bulkhead cooling path as the torque index, which is correlated with output torque, increases when the vehicle speed index, which is correlated with vehicle speed, falls below a first threshold.

[0009] With the above configuration, at low vehicle speeds, the cooling capacity of the bulkhead can be increased as the motor generates more heat.

[0010] The cooling system may adjust the amount of heat transfer medium supplied to the bulkhead cooling path to a first supply amount when the vehicle speed index is below a first threshold and the torque index is below a second threshold. The cooling system may adjust the amount of heat transfer medium supplied to the bulkhead cooling path to a second supply amount that is greater than the first supply amount when the vehicle speed index is below a first threshold and the torque index is above a second threshold.

[0011] With the above configuration, when the vehicle speed is low, the cooling capacity of the bulkhead can be increased in proportion to the increased output torque of the motor (i.e., in proportion to the increased heat generated by the motor).

[0012] The cooling system may gradually or continuously reduce the amount of heat transfer medium supplied to the bulkhead cooling path as the vehicle speed index, which is correlated with vehicle speed, increases when the torque index, which is correlated with output torque, exceeds a second threshold.

[0013] With the above configuration, when the motor's output torque is high, the cooling capacity of the bulkhead can be reduced as the vehicle speed increases. This allows the reduced cooling capacity of the bulkhead to be allocated to other parts, such as the motor. This makes it possible to optimize the overall cooling capacity of the drive system.

[0014] When the torque index exceeds the second threshold and the vehicle speed index is lower than the first threshold, the cooling system may adjust the supply amount of the heat medium to the partition cooling path to the second supply amount. When the torque index exceeds the second threshold and the vehicle speed index exceeds the first threshold, the cooling system may adjust the supply amount of the heat medium to the partition cooling path to a third supply amount smaller than the second supply amount.

[0015] According to the above configuration, when the output torque is large, as the vehicle speed increases, the cooling capacity of the partition can be reduced. As a result, the reduction in the cooling capacity of the partition can be allocated to other parts such as the motor.

[0016] At least a motor may be stored in the first chamber. The cooling system may further include a motor cooling path for supplying the heat medium to the motor. The cooling system may switch the ratio of the supply amount of the heat medium supplied to the partition cooling path to the supply amount of the heat medium supplied to the motor cooling path between at least two levels according to the combination of the vehicle speed index correlated with the vehicle speed and the torque index correlated with the output torque.

[0017] According to the above configuration, the allocation of the cooling capacity between the partition and the motor can be controlled by the ratio of the supply amounts of the heat medium between the partition and the motor.

[0018] When the torque index exceeds the second threshold, the cooling system may decrease the ratio stepwise or continuously as the vehicle speed index increases.

[0019] According to the above configuration, when the output torque of the motor is large, as the vehicle speed increases, more cooling capacity can be allocated to the motor than to the partition. Since the energy consumption of the motor can be suppressed, efficiency can be improved.

[0020] When the torque index exceeds the second threshold and the vehicle speed index is below the first threshold, the cooling system may adjust the ratio to the first ratio. When the torque index exceeds the second threshold and the vehicle speed index exceeds the first threshold, the cooling system may adjust the ratio to a second ratio smaller than the first ratio.

[0021] According to the above configuration, when the output torque is large, as the vehicle speed increases, more cooling capacity can be allocated to the motor than to the partition wall.

[0022] The heat medium may be in a liquid state. The cooling system may further include a pump for supplying the heat medium to the partition wall cooling path and the motor cooling path. The cooling system may further include a flow rate adjustment unit capable of adjusting the ratio of the supply amount of the heat medium supplied to the partition wall cooling path to the supply amount of the heat medium supplied to the motor cooling path.

[0023] According to the above configuration, the pump and the flow rate adjustment unit can allocate the cooling capacity between the motor and the partition wall.

[0024] The heat medium may be oil. The first chamber may further include a gear compartment for storing the gear unit. The oil may be stored in the first chamber.

[0025] The casing may further include a storage portion for storing oil at the lower part of the gear compartment. A part of the gear unit may be immersed in the oil stored in the storage portion. The cooling system may further include a pump for sending the oil stored in the storage portion to the partition wall cooling path. The cooling system may switch the delivery amount of the pump between at least two levels according to the combination of a vehicle speed index correlated with the vehicle speed and a torque index correlated with the output torque.

[0026] According to the above configuration, the allocation of the oil supply capacity between the partition wall and the gear unit can be controlled by the delivery amount of the pump.

[0027] The cooling system may gradually or continuously reduce the amount of oil delivered to the bulkhead cooling path as the vehicle speed index increases.

[0028] With the above configuration, the amount of oil stored in the reservoir can increase as the vehicle speed increases. Therefore, as the vehicle speed increases, more of the lubrication capacity provided by the oil can be allocated to the gears. This makes it possible to suppress gear seizure and other issues.

[0029] The first chamber may further include a motor compartment for housing the motor. The cooling system may further include a motor cooling path for supplying oil to the motor. A pump may deliver oil stored in the reservoir to the bulkhead cooling path and the motor cooling path. Depending on a combination of vehicle speed and torque indicators, the cooling system may switch the ratio of the amount of oil supplied to the bulkhead cooling path to the amount of oil supplied to the motor cooling path between at least two levels.

[0030] According to the above configuration, the allocation of oil supply capacity between the bulkhead, gear unit, and motor can be controlled.

[0031] The cooling system may gradually or continuously decrease the ratio as the vehicle speed index increases when the torque index exceeds the second threshold.

[0032] With the above configuration, when the motor's output torque is high, the higher the vehicle speed, the more cooling capacity can be allocated to the motor than to the bulkhead. This reduces the motor's energy consumption, thus improving efficiency. [Examples]

[0033] (Configuration of drive unit 1) Figure 1 shows a schematic configuration of the drive unit 1 of this embodiment. The drive unit 1 is an integrated device in which a motor and gear unit and a power conversion unit for controlling the motor are housed in the same casing. Figure 1 shows the drive unit 1 mounted on a vehicle (electric vehicle). Direction FR indicates the front in the longitudinal direction of the vehicle. Direction RH indicates the right in the lateral direction (or width direction) of the vehicle. Direction UP indicates the upward direction in the vertical direction of the vehicle. In Figure 1, multiple shafts (motor shaft 43, counter shaft 52, drive shaft 57) are shown unfolded so that they are located in the same plane. The cooling path is shown by a solid line.

[0034] The drive unit 1 is controlled by the control unit 2. The control unit 2 includes, for example, a CPU, RAM, ROM, input / output interface, etc. The control unit 2 is connected to the power conversion unit 21, oil pump 64, variable orifice 66, etc., by signal lines (not shown).

[0035] The drive unit 1 includes a casing 10. The casing 10 has a first chamber 11 and a second chamber 12 separated from each other by a partition wall 13.

[0036] The first compartment 11 comprises a motor compartment 31 and a gear compartment 32. The two compartments are separated from each other by a partition wall 35. A motor 40 is housed in the motor compartment 31. The motor 40 comprises a stator 41, a rotor 42, and a motor shaft 43. The stator 41 has a cylindrical shape. The rotor 42 is rotatably arranged inside the stator 41. The motor shaft 43 is arranged coaxially with the center of rotation of the rotor 42. The motor shaft 43 is hollow.

[0037] The gear compartment 32 houses the gear unit 50. The gear unit 50 comprises a shaft gear 51, a countershaft 52, a first counter gear 53, a second counter gear 54, a ring gear 55, and a differential gear 56. The shaft gear 51 is attached to the motor shaft 43. This mechanically connects the gear unit 50 and the motor 40.

[0038] A first counter gear 53 and a second counter gear 54 are attached to the counter shaft 52. The first counter gear 53 meshes with the shaft gear 51. The second counter gear 54 meshes with the ring gear 55. The ring gear 55 is attached to the differential gear 56. The differential gear 56 drives the drive shaft 57. When the rotation of the motor 40 is transmitted to the drive shaft 57, a pair of wheels (not shown) connected to the drive shaft 57 rotate. This causes the vehicle to move.

[0039] A reservoir 33 is provided at the bottom of the gear compartment 32. Oil 34 is stored in the reservoir 33. The oil 34 functions as a heat transfer medium to cool the motor 40, the partition wall 13, and the gear unit 50, and also functions as a lubricant for the gear unit 50. In other words, the oil 34 has both a cooling function and a lubricating function. A portion of the gear unit 50 is immersed in the oil 34 stored in the reservoir 33. In the example in Figure 1, the lower part of the differential gear 56 is immersed in the oil 34. The stored oil 34 is churned up by the differential gear 56, lubricating each gear of the gear unit 50.

[0040] The drive unit 1 is also equipped with a cooling system 60. The cooling system 60 is a system that circulates the oil 34 stored in the first chamber 11. The cooling system 60 includes a motor cooling path 61, a partition wall cooling path 62, a strainer 63, an oil pump 64, an oil cooler 65, and a variable orifice 66.

[0041] The motor cooling path 61 is a path that supplies oil to the motor 40. The motor cooling path 61 is a path that goes from the strainer 63, through the oil pump 64 and oil cooler 65, to the motor 40. The strainer 63 is located in the storage section 33. The oil pump 64 draws in the oil 34 from the storage section 33 through the strainer 63. The oil pump 64 then sends the drawn-in oil to the motor cooling path 61 and the partition cooling path 62. The amount of oil sent by the oil pump 64 is controlled by the control device 2. The details of the control of the amount of oil sent by the oil pump 64 will be described later. The oil cooler 65 is a heat exchanger that cools the oil by heat exchange with a refrigerant. The oil sent from the oil cooler 65 is introduced into the upper part of the motor compartment 31.

[0042] The motor cooling path 61 branches into an upper path 61u and an axial path 61a within the motor compartment 31. The upper path 61u is provided with multiple discharge holes that open radially downward. The stator 41 is cooled by the oil discharged downward from the discharge holes. The motor shaft 43 has a hollow shape (cylindrical shape), and an axial path 61a is provided along its axis. The axial path 61a is provided with multiple discharge holes that penetrate radially. The oil that flows out from the discharge holes flows down to the bottom of the motor compartment 31 through holes (not shown) in the rotor 42.

[0043] The partition wall cooling path 62 is a path that supplies oil to the partition wall 13. The partition wall cooling path 62 is a path that goes from the branch 61b of the motor cooling path 61, through the variable orifice 66 and the in-wall circulation path 62w, to the motor compartment 31. The variable orifice 66 is a flow rate adjustment unit for controlling the flow rate of oil that branches off and flows into the partition wall cooling path 62. In other words, the variable orifice 66 controls the ratio of the amount of oil supplied to the partition wall cooling path 62 to the amount of oil supplied to the motor cooling path 61. The control details of the variable orifice 66 will be described later. The in-wall circulation path 62w is a circulation path located inside the partition wall 13.

[0044] The oil supplied to the motor 40 by the motor cooling path 61 and the oil supplied to the partition wall 13 by the partition wall cooling path 62 flow downwards within the motor compartment 31. The flowing oil returns to the storage section 33 in the gear compartment 32 via communication holes (not shown) provided in the partition wall 35.

[0045] The second chamber 12 houses the power conversion unit 21. The power conversion unit 21 is the component that controls the power supplied to the motor 40 and the power generated. Examples of components included in the power conversion unit 21 include an inverter and a converter. The power conversion unit 21 is electrically connected to the motor 40 by a busbar 22. The power conversion unit 21 is also equipped with a cooling water passage 23. The cooling water passage 23 includes a water pump 24 and a radiator 25. Cooling water circulates through the cooling water passage 23.

[0046] (Oil supply control) The cooling system 60 controls the oil pump 64 and the variable orifice 66 according to a combination of a vehicle speed index and a torque index. The vehicle speed index is an index correlated with the vehicle speed. In this embodiment, the vehicle speed index is the rotational speed of the motor 40. The torque index is an index correlated with the output torque of the motor 40. In this embodiment, the torque index is the torque command value of the motor 40.

[0047] Let's explain this in detail using Figure 2. Figure 2 shows the torque curve TC of motor 40. The horizontal axis of Figure 2 represents the rotational speed N of motor 40, and the vertical axis represents the output torque Te. The rotational speed N has a predetermined first threshold value TV1. The output torque Te has a predetermined second threshold value TV2. Note that there are various ways to determine the first threshold value TV1 and the second threshold value TV2. These threshold values ​​may be fixed values, for example, or they may be calculated each time based on a formula or table.

[0048] At rotational speed N, the range below the first threshold TV1 is defined as the low-speed range LS, and the range above the first threshold TV1 is defined as the high-speed range HS. In the low-speed range LS, the cooling capacity of the power conversion unit 21 is lower than in the high-speed range HS. This is because as the vehicle speed decreases, the amount of airflow passing through the radiator 25 decreases, thus reducing the amount of heat dissipated by the radiator 25. Here, airflow refers to the flow of air that enters the vehicle when the vehicle is in motion. As the vehicle speed increases, the amount of airflow also increases. This is also because, as the vehicle speed decreases, the ambient temperature around the drive unit 1 may not decrease as easily. Furthermore, in the high-speed range HS, seizure of the gear unit 50 is more likely to occur than in the low-speed range LS. This is because the higher the rotational speed of the gear unit 50, the more likely oil film rupture is to occur.

[0049] In terms of output torque Te, the range below the second threshold TV2 is defined as the low torque range LT, and the range above the second threshold TV2 is defined as the high torque range HT. An example of a situation in which the low torque range LT occurs is when driving downhill or on flat ground. An example of a situation in which the high torque range HT occurs is when driving uphill. In the high torque range HT, the amount of heat generated by the motor 40 is greater than in the low torque range LT. This is because the current flowing through the motor 40 increases as the output torque Te increases.

[0050] Based on the above, the torque curve TC region is classified into four areas: low-speed low-torque region R1, low-speed high-torque region R2, high-speed low-torque region R3, and high-speed high-torque region R4. The low-speed low-torque region R1 is defined by the low-speed range LS and the low-torque range LT. The low-speed high-torque region R2 is defined by the low-speed range LS and the high-torque range HT. The high-speed low-torque region R3 is defined by the high-speed range HS and the low-torque range LT. The high-speed high-torque region R4 is defined by the high-speed range HS and the high-torque range HT. The low-speed low-torque region R1 and the high-speed low-torque region R3 are regions where the accelerator opening is relatively small. The low-speed high-torque region R2 and the high-speed high-torque region R4 are regions where the accelerator opening is relatively large.

[0051] The table in Figure 3 shows the allocation of oil supply among the three components: the partition wall 13, the motor 40, and the gear unit 50. Here, "priority" means supplying a larger amount of oil. The cooling system 60 changes the parts to which oil is prioritized in each of the low-speed, low-torque region R1 and the high-speed, high-torque region R4. This will be explained in detail.

[0052] In the low-speed, low-torque range R1, the motor 40 generates little heat, and oil depletion in the gear unit 50 is less likely to occur. Therefore, there is no need to prioritize oil supply to the motor 40, gear unit 50, or partition wall 13.

[0053] In the low-speed, high-torque region R2, oil supply to the motor 40 and the partition wall 13 is prioritized over oil supply to the gear unit 50. The reason for prioritizing the cooling of the motor 40 is that the amount of heat generated by the motor 40 increases in the high-torque range HT. The reason for prioritizing the cooling of the partition wall 13 is that the cooling capacity of the power conversion unit 21 decreases in the low-speed range LS. When the cooling capacity of the power conversion unit 21 decreases, it becomes difficult to remove the amount of heat transferred from the motor 40 through the partition wall 13. Therefore, the heat load on the power conversion unit 21 due to the heat generated by the motor 40 increases. By improving the cooling function of the partition wall 13, heat transfer from the motor 40 can be suppressed. In other words, the decrease in the cooling capacity of the power conversion unit 21 due to the decrease in vehicle speed can be compensated for by the cooling capacity of the partition wall 13.

[0054] In the high-speed, low-torque region R3, oil supply to the gear unit 50 takes precedence over oil supply to the motor 40 and the partition wall 13. This is because, in the high-speed range HS, the gear unit 50 is prone to seizing. Also, in the low-torque range LT, the motor 40 generates less heat.

[0055] In the high-speed, high-torque region R4, oil supply to the motor 40 and gear unit 50 is prioritized over oil supply to the partition wall 13. The reason for prioritizing the cooling of the motor 40 is that the amount of heat generated by the motor 40 increases in the high-torque range HT. The reason for prioritizing the lubrication of the gear unit 50 is that seizure of the gear unit 50 is more likely to occur in the high-speed range HS. The reason for not prioritizing the cooling of the partition wall 13 is that the amount of airflow during travel increases in the high-speed range HS, which increases the cooling capacity of the power conversion unit 21.

[0056] (Operation and effects of the cooling system 60) The specific operation of the cooling system 60 for controlling the oil supply as shown in Figure 3 will be explained. In the low-speed, low-torque region R1, the cooling system 60 adjusts the amount of oil supplied to the partition wall cooling path 62 to a first supply amount (see Figure 3, region A1). In the low-speed, high-torque region R2, the cooling system 60 adjusts the amount of oil supplied to the partition wall cooling path 62 to a second supply amount that is greater than the first supply amount (see region A2). Control to increase the oil supply amount can be achieved by increasing the oil distribution ratio to the partition wall cooling path 62 using the variable orifice 66, and by increasing the output amount of the oil pump 64.

[0057] In other words, in the low-speed range LS, the cooling system 60 gradually increases the amount of oil supplied to the bulkhead cooling path 62 as the output torque Te increases (see regions A1 and A2). This allows the cooling capacity of the bulkhead 13 to be increased in proportion to the increased output torque of the motor 40 (i.e., in proportion to the increased heat generated by the motor 40) when the vehicle speed is low. This makes it possible to suppress the thermal load on the power conversion unit 21 due to the heat generated by the motor 40.

[0058] In the low-speed, high-torque region R2, the cooling system 60 adjusts the amount of oil supplied to the partition wall cooling path 62 to a second supply amount (see Figure 3, region A2). In the high-speed, high-torque region R4, the cooling system 60 adjusts the amount of oil supplied to the partition wall cooling path 62 to a third supply amount, which is smaller than the second supply amount (see region A3).

[0059] In other words, in the high torque range HT, the cooling system 60 gradually reduces the amount of oil supplied to the bulkhead cooling path 62 as the vehicle speed increases (see regions A2 and A3). This allows the cooling capacity of the bulkhead 13 to be reduced in proportion to the vehicle speed when the output torque is high. Therefore, the reduced cooling capacity of the bulkhead 13 can be allocated to other parts such as the motor 40. This makes it possible to optimize the overall cooling capacity of the drive unit 1.

[0060] In the low-speed, high-torque region R2, the cooling system 60 adjusts the ratio of the amount of oil supplied to the partition wall cooling path 62 to the amount of oil supplied to the motor cooling path 61 to a first ratio (see Figure 3, regions A2 and A4). In the high-speed, high-torque region R4, the cooling system 60 adjusts the above ratio to a second ratio, which is smaller than the first ratio (see regions A3 and A5). This reduction in the above ratio can be achieved by decreasing the oil distribution ratio from the motor cooling path 61 to the partition wall cooling path 62 using the variable orifice 66.

[0061] In other words, in the high torque range HT, the cooling system 60 gradually reduces the oil supply ratio to the bulkhead cooling path 62 as the vehicle speed increases. This allows the motor 40 to allocate more cooling capacity to the motor 40 than to the bulkhead 13 as the vehicle speed increases, especially when the motor 40 has high output torque. This reduces the energy consumption of the motor 40, thus improving efficiency.

[0062] The cooling system 60 prioritizes oil lubrication of the gear unit 50 in the high-speed, high-torque region R4 (see region A7) over oil lubrication of the gear unit 50 in the low-speed, high-torque region R2 (see region A6). Control to enhance oil lubrication of the gear unit 50 can be achieved by reducing the amount of oil delivered from the oil pump 64, thereby raising the oil level in the reservoir 33.

[0063] In other words, the cooling system 60 gradually reduces the amount of oil delivered from the oil pump 64 as the vehicle speed increases. This allows more of the oil's lubrication capacity to be allocated to the gear unit 50 as the vehicle speed increases, thereby suppressing seizure of the gear unit 50.

[0064] Although embodiments have been described in detail above, these are merely illustrative and do not limit the scope of the claims. The technologies described in the claims include various modifications and changes to the specific examples illustrated above. The technical elements described in this specification or drawings exhibit technical usefulness individually or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Furthermore, the technologies illustrated in this specification or drawings achieve multiple objectives simultaneously, and achieving even one of these objectives constitutes technical usefulness in itself.

[0065] (First variation) Figure 4 shows the drive unit 101 according to the first modified example. In the following description, parts common to the modified drive unit and the drive unit 1 of this embodiment (Figure 1) will be given the same reference numerals, and their explanation will be omitted. The drive unit 101 is equipped with a cooling pipe 162p instead of the in-wall circulation path 62w of the drive unit 1. The cooling pipe 162p is arranged inside the motor compartment 31 so as to face the partition wall 13. The cooling pipe 162p is provided with a plurality of discharge holes that open toward the partition wall 13. Oil is ejected toward the partition wall 13 from each of the plurality of discharge holes. The partition wall 13 can be cooled.

[0066] (Second variation) Figure 5 shows a drive unit 201 according to a second modified example. The drive unit 201 further includes a gear cooling path 263. The gear cooling path 263 is a path that supplies oil to the gear unit 50. The gear cooling path 263 is a path that goes from the branch 61c of the motor cooling path 61, through the variable orifice 268, to the gear compartment 32. A variable orifice 267 is also located in the motor cooling path 61. The cooling system 60 controls the variable orifices 66, 267, and 268. This allows for individual control of the oil flow rate in each of the partition wall cooling path 62, the motor 40's axial path 61a and upper path 61u, and the gear cooling path 263. Note that the gear cooling path 263 can be omitted in the drive unit 201.

[0067] (Third variation) The position of the second chamber 12 can vary. For example, as shown in the third modified example of the drive unit 301 in Figure 6, the second chamber 12 may be positioned adjacent to the gear compartment 32. This allows the unnecessary space in the gear compartment 32 to be repurposed for the second chamber 12, making it possible to further miniaturize the drive unit 301.

[0068] (Fourth variation) The heat transfer medium used to cool the partition wall 13 is not limited to oil. For example, as shown in the drive unit 401 according to the fourth modified example in Figure 7, the partition wall 13 may be cooled by cooling water. In the drive unit 401, the second chamber 12 is located adjacent to and above the motor compartment 31. The ring gear 55 and drive shaft 57 are located on the front side of the vehicle (i.e., the back of the page) and are therefore shown with dotted lines.

[0069] The cooling water channel 23 branches at branch 23b into the power conversion unit cooling path 23p and the partition wall cooling path 23w. The partition wall cooling path 23w is the path that returns to the water pump 24 from branch 23b via the variable orifice 26 and the in-wall circulation path 62w. The variable orifice 26 is a flow rate adjustment unit for controlling the flow rate of the cooling water that branches off into the partition wall cooling path 23w. In other words, the variable orifice 26 controls the ratio of the amount of cooling water supplied to the partition wall cooling path 23w to the amount of cooling water supplied to the power conversion unit cooling path 23p.

[0070] In the fourth modified example, the drive unit 401 can also control the amount of heat transfer medium supplied, similar to the drive unit 1 in this embodiment. That is, the amount of cooling water supplied to the partition wall cooling path 23w can be appropriately adjusted according to the vehicle speed and output torque. Therefore, even under conditions where cooling the partition wall 13 is difficult (e.g., low vehicle speed conditions, high torque conditions), the partition wall 13 can be properly cooled.

[0071] (Other variations) The vehicles on which the drive system described herein is installed are not limited to electric vehicles. The drive system described herein can be installed in, for example, hybrid vehicles and plug-in hybrid vehicles. In this case, the drive system described herein may house multiple motors or a planetary gear mechanism within the casing. Furthermore, the drive system described herein is also applicable to vehicles that use electric motors for at least part of their propulsion, such as fuel cell vehicles.

[0072] The first threshold value TV1 for dividing the vehicle speed range and the second threshold value TV2 for dividing the torque range are not limited to one, but may be multiple. Furthermore, the adjustment of the oil supply amount by the cooling system 60 is not limited to a stepwise change. For example, the oil supply amount may be continuously changed in response to changes in vehicle speed or output torque.

[0073] The vehicle speed indicator can be varied; for example, the actual vehicle speed may be used. The torque indicator can be varied; for example, the current value of the motor 40 may be used, or the torque measurement value from the torque sensor may be used.

[0074] The airflow through the vehicle may pass not only through the radiator 25 but also through the surface of the drive unit casing 10. Additionally, ribs that function as heat dissipation fins may be provided on the surface of the casing 10. This reduces the heat load transmitted from the motor 40 and gear unit 50 to the power conversion unit 21. [Explanation of Symbols]

[0075] 1: Drive unit 10: Casing 11: First chamber 12: Second chamber 21: Power conversion unit 33: Storage section 34: Oil 40: Motor 50: Gear unit 60: Cooling system 61: Motor cooling path 62: Partition cooling path 64: Oil pump 66: Variable orifice N: Rotational speed Te: Output torque

Claims

1. A drive system for a vehicle, Motor and, A gear unit mechanically connected to the motor, A power conversion unit electrically connected to the motor, A casing having a first chamber and a second chamber separated from each other by a partition wall, wherein at least one of the motor and the gear unit is housed in the first chamber and the power conversion unit is housed in the second chamber, A cooling system that circulates a heat transfer medium in at least one of the first chamber and the second chamber, Equipped with, The cooling system includes a partition wall cooling path that supplies the heat transfer medium to the partition wall, and the amount of heat transfer medium supplied to the partition wall cooling path is greater when the vehicle speed is low and the output torque of the motor is high than when the vehicle speed is high and the output torque of the motor is low. The partition wall cooling path includes a portion that ejects the heat transfer medium into the partition wall. Drive unit.

2. A drive system for a vehicle, Motor and, A gear unit mechanically connected to the motor, A power conversion unit electrically connected to the motor, A casing having a first chamber and a second chamber separated from each other by a partition wall, wherein at least one of the motor and the gear unit is housed in the first chamber and the power conversion unit is housed in the second chamber, A cooling system that circulates a heat transfer medium in at least one of the first chamber and the second chamber, Equipped with, The cooling system includes a partition cooling path for supplying the heat transfer medium to the partition wall, a motor cooling path for supplying the heat transfer medium to the motor, and a flow rate adjustment unit capable of adjusting the ratio of the amount of heat transfer medium supplied to the partition cooling path to the amount of heat transfer medium supplied to the motor cooling path, wherein the amount of heat transfer medium supplied to the partition cooling path is greater when the vehicle speed is low and the output torque of the motor is high than when the vehicle speed is high and the output torque of the motor is low. Drive unit.

3. The drive device according to claim 2, wherein the partition wall cooling path is a path that branches off from the motor cooling path, passes through the flow rate adjustment unit, and reaches the partition wall.

4. The drive device according to claim 2, wherein the flow rate adjustment unit includes a variable orifice.

5. The drive device according to claim 1 or 2, wherein the cooling system increases the amount of the heat transfer medium supplied to the partition wall cooling path in stages or continuously as the torque index correlated with the output torque increases when the vehicle speed index correlated with the vehicle speed falls below a first threshold.

6. The cooling system is, When the vehicle speed index falls below the first threshold and the torque index falls below the second threshold, the amount of heat transfer medium supplied to the partition wall cooling path is adjusted to the first supply amount. The drive device according to claim 5, wherein when the vehicle speed index falls below the first threshold and the torque index exceeds the second threshold, the amount of heat transfer medium supplied to the partition wall cooling path is adjusted to a second supply amount that is greater than the first supply amount.

7. The drive device according to claim 1 or 2, wherein the cooling system reduces the amount of the heat transfer medium supplied to the partition wall cooling path in stages or continuously as the vehicle speed index correlated with the vehicle speed increases when the torque index correlated with the output torque exceeds a second threshold.

8. The cooling system is, When the torque index exceeds the second threshold and the vehicle speed index falls below the first threshold, the amount of heat transfer medium supplied to the partition wall cooling path is adjusted to the second supply amount. The drive device according to claim 7, wherein when the torque index exceeds the second threshold and the vehicle speed index exceeds the first threshold, the amount of heat transfer medium supplied to the partition cooling path is adjusted to a third supply amount that is smaller than the second supply amount.

9. The first chamber houses at least the motor, The drive device according to claim 1 or 2, wherein the cooling system further includes a motor cooling path for supplying the heat transfer medium to the motor, and switches the ratio of the amount of the heat transfer medium supplied to the partition cooling path to the amount of the heat transfer medium supplied to the motor cooling path between at least two levels, depending on a combination of a vehicle speed index correlated with the vehicle speed and a torque index correlated with the output torque.

10. The drive device according to claim 9, wherein the cooling system reduces the ratio in stages or continuously as the vehicle speed index increases when the torque index exceeds a second threshold.

11. The cooling system is, When the torque index exceeds the second threshold and the vehicle speed index falls below the first threshold, the ratio is adjusted to the first ratio. The drive device according to claim 10, wherein when the torque index exceeds the second threshold and the vehicle speed index exceeds the first threshold, the ratio is adjusted to a second ratio that is smaller than the first ratio.

12. The heat transfer medium is liquid, The cooling system is, A pump that supplies the heat transfer medium to the partition wall cooling path and the motor cooling path, A flow rate adjustment unit capable of adjusting the ratio of the amount of heat transfer medium supplied to the partition wall cooling path to the amount of heat transfer medium supplied to the motor cooling path, The drive device according to claim 9, further comprising:

13. The heat transfer medium is oil. The first chamber further comprises a gear compartment for housing the gear unit, The drive device according to claim 1 or 2, wherein the oil is stored in the first chamber.

14. The casing further includes a reservoir for storing the oil at the bottom of the gear compartment. A portion of the gear unit is immersed in the oil stored in the reservoir. The cooling system further includes a pump that sends the oil stored in the storage section to the partition wall cooling path. The drive device according to claim 13, wherein the cooling system switches the amount of the pump delivered between at least two levels according to a combination of a vehicle speed index correlated with the vehicle speed and a torque index correlated with the output torque.

15. The drive device according to claim 14, wherein the cooling system reduces the amount of oil delivered to the bulkhead cooling path in stages or continuously as the vehicle speed index increases.

16. The first chamber further comprises a motor compartment for housing the motor, The cooling system further includes a motor cooling path for supplying the oil to the motor, The pump sends the oil stored in the storage section to the partition cooling path and the motor cooling path. The drive device according to claim 15, wherein the cooling system switches the ratio of the amount of oil supplied to the partition cooling path to the amount of oil supplied to the motor cooling path between at least two levels, depending on the combination of the vehicle speed index and the torque index.

17. The drive device according to claim 16, wherein the cooling system reduces the ratio in stages or continuously as the vehicle speed index increases when the torque index exceeds a second threshold.

18. The cooling system is, When the vehicle speed index falls below the first threshold and the torque index exceeds the second threshold, the ratio is adjusted to the first ratio. The drive device according to claim 17, wherein when the vehicle speed index exceeds the first threshold and the torque index exceeds the second threshold, the ratio is adjusted to a second ratio that is smaller than the first ratio.

19. The drive device according to claim 18, further comprising a flow rate adjustment unit capable of adjusting the ratio of the amount of heat transfer medium supplied to the partition wall cooling path to the amount of heat transfer medium supplied to the motor cooling path.

20. The drive device according to claim 1 or 2, wherein the partition wall cooling path comprises a flow path disposed within the partition wall.

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